The invention provides a cable joint health diagnosis and heat fault pre-warning system. The system comprises a measurement control module, a communication module, a display module, an alarming module, a temperature sensor, a humidity sensor, a gas sensor, a stress sensor, a hoop metal strap, an environmental temperature sensor, an environmental humidity sensor and a control center network server. The different sensors are combined for online monitoring of cable joints, and by a manner different from an existing manner of alarming after occurrence of faults, unhealthy statuses and operation environments of the cable joints are measured and analyzed, such as temperature, humidity, gas, smoke, expansion, breathability, environmental temperature, environmental humidity and the like, and consequently low cost is guaranteed while sensitivity and accuracy of the pre-warning system are greatly improved. Therefore, health diagnosis and heat fault pre-warning of the cable joints are realized to effectively take preventive measures, reliability in operation of the cable joints and even an electric power system is improved, cable joint fault treatment time is shortened, and economic loss caused by faults of the cable joints is greatly reduced.